Overview
Complex regional pain syndrome (CRPS) is characterised by spontaneous and/or evoked pain that is out of proportion to the triggering event and beyond the normal timeframe after the event. It is regional (usually not confined to a specific dermatome) and complex due to the variety of signs and symptoms that can arise.
It is thought that inflammation leads to altered pain perception in the nervous system, giving rise to CRPS.
Causes
CRPS is often triggered by trauma, but can be subdivided into:
- CRPS I – pain developing in the absence of an identifiable nerve injury
- CRPS II – pain in the presence of damage to a major nerve
Epidemiology
- More common with increasing age
- More common and more severe in women
- In most cases, the arm and the leg are affected
- Fractures are the most common trigger
Presentation
The symptoms of CRPS can vary significantly:
- Pain – usually burning and there may be neuropathic pain
- This pain is usually out of proportion to the triggering event
- Allodynia – perceiving pain from a non-painful stimulus
- Hyperalgesia – painful stimuli cause more pain than usual
- Swelling
- Vasomotor abnormalities – e.g. spontaneous temperature changes with the affected side being warmer/cooler than the other
- Sweating
- Goosebumps
- Oedema
Differential Diagnoses
Nerve entrapment
- Signs and symptoms are usually within the distribution of the affected nerve e.g. carpal tunnel syndrome
Investigations
- None – clinical diagnosis
- Consider EMG if focal nerve disorders are suspected
Management
- Referral to a specialist pain clinic for confirmation of diagnosis
- Conservative management with physiotherapy and rehabilitation
- Multidisciplinary team management
- Analgesia using simple analgesia + consider drugs for neuropathic pain
Patient Advice
- Patients should be educated on the importance of maintaining limb function and how excess exercise can cause pain, and how too little can as well. They need to find a middle ground.
Complications and Prognosis
Complications
- Depression
- Stiffness secondary to immobilisation
- Osteoporosis secondary to immobilisation
- Severe skin infections
Prognosis
- There is no cure, however, most patients improve
- They may have acute flares of pain but these do not indicate that CRPS is worsening
- If CRPS is undiagnosed and unmanaged, it can spread to other extremities
